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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.0//EN">
<html lang=en>
<head>
<title>CUCC Expo Handbook: rigging - artificial belays - bolts</title>
</head>
<body>
<center><h2>Bolt belays - placing and using</h2></center>
Most people on Austria expeditions will be familiar with the use of bolt
belays from trips in the UK. In Austria, caves already explored will have
bolts with the hangers removed, which can be quite hard to spot. Anyone
hoping for a join-the-dots trip will be disappointed. These bolts can usually
be found fairly easily by anyone familiar with expo rigging, <i>provided a
good rigging guide was drawn up by the previous explorers</i>. Y-hangs are
common at pitch heads, so check that you find both bolts. Lower down, it is
as well to know whether a bolt has been placed for a rebelay or a deviation,
as it may not become obvious which until some way down the pitch. Such a
rigging guide is also useful to show which existing bolts should <b>not</b>
be used. Inevitably some bolts will be badly placed, or may become damaged.
It is as important not to use these as it is to find the right ones.
<p>For new pitches when, as is often the case, good natural belays are
scarce, you must place one or more bolts yourself. Doing so puts you in
a position of responsibility both for the safety of future users of that
bolt and for the conservation of the cave. The aim should always be to
put in good bolts which will contribute to a safe rig with a minimum of
further bolting needed.
<p>This is easier said than done, and there is ample evidence of this in
caves CUCC have explored over the years. The best place for a bolt may
be far from obvious until the pitch has been descended. Or maybe the best
place is obvious, but that place is hard to reach. It is tempting to try
to reach for the best placement, but overstretching or an insecure perch
may lead to a poor bolt in the perfect place. This is very much to be
avoided, since it is now impossible to put a good bolt in the perfect
place - the rock around the first placement will have been stressed and
another bolt should not be placed closer than about 20 cm from it.
<h3>Placing bolts</h3>
Placing a bolt is a simple matter of drilling a hole and inserting a rock
anchor. The bottom end of the rock anchor is expanded by some mechanism,
and thus grips tightly in the hole, resisting any attempt to pull it
out. The anchor is strongest if loaded at right angles to its axis, ie.
parallel with the rock surface. Hence for a vertical pitch, it is normally
best to place the anchor in a vertical rock surface.
<p>The hole may be made in either of two ways. For the penalty of carrying
considerable extra weight, a cordless power drill is the quickest way to
drill the hole. The heaviest item is the drill battery, which must, of
course, be removed from the cave each time it needs charging. This method is
of the most use where a lot of bolts need to be placed on a pitch series
relatively accessible from an entrance. Lots of bolts are also needed for
climbs up or exposed traverses to reach inaccessible passages.
<p><center><a href="../smkridge/161/l/boltin.htm"><img alt="(36k image)"
src="../smkridge/161/t/boltin.jpg" width=113 height=152></a>&nbsp;
&nbsp;<a href="l/bosch.htm"><img alt="(73k image)"
src="t/bosch.jpg" width=200 height=200></a><br>
<b>Bolting by Hand&nbsp; &nbsp; &nbsp;Using the Drill</b></center>
<p>The older (and more reliable, but slower) method is to use the anchor
itself as the drill bit, driven in by use of a hammer. 8mm self-drilling
rock anchors have teeth around their bottom for this purpose. The anchor is
attached to a bolt driver, which is then repeatedly pounded with a hammer,
whilst rotating the anchor by hand every couple of whacks. When this gets
a little stiff, the anchor is pulled out of its hole and the dust and rock
chips blown out. The process is repeated until the top of the anchor is
just below the rock surface. A small conical "wedge" is then inserted into
end of the anchor (thin end into the anchor) and the pair put back in the
hole. Three or four good hard whacks with the hammer "set" the anchor by
driving the wedge into the bottom end, expanding it. Beware of hitting it too
many times, as this will start to weaken the rock around the anchor.
<p>The hole produced by the power drill is a different shape from that
produced by hand - since the power drill bit has a pointed end. For this
reason, if a self-drilling anchor is set into a powerdrill hole, the wedge
will not be driven into the anchor and an unsafe placement will result.
Either use a form of anchor specially intended for the power drilled holes,
or finish the hole off with a self-drilling anchor to ensure the bottom end
is square.
<hr>
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